Yeah, I had looked into getting a Mifi device, but that would be another $20 a month, whereas we could increase our phone bandwidth by 20gb a month and it would only cost $45 more. We have two phones, so if one was tied up with internet, it wouldn't be a problem to still be able to use the other one.
Part of the reason I wanted a personal wifi network is so I can connect my devices to each other without having to go through an RV park network. I was thinking about it more, and I think I'm going with a Raspberry Pi and a USB powered wifi router. That way I can still connect most of them together if I run out of power for some reason, and they use far less power than the mac mini/airport combo. They are much smaller too, and I can hide them away somewhere out of sight. The Pi automatically boots too, so if i need to connect it to wifi, I can ssh in and connect it to wifi and have it set up to share the internet connection via ethernet to the router.